In general, vibration and noise occur due to vertical reciprocating motion of a piston and a connecting rod in an engine of a vehicle, a rotational inertial force of a crank shaft connected to the connecting rod that reciprocates vertically, and due to shaking of the crank shaft which occurs in a longitudinal direction of the crank shaft when the crank shaft rotates.
In order to prevent such vibration and noise from being transferred to a vehicle body, the engine is mounted on the vehicle body using an engine mount that is made of a rubber material having predetermined elasticity.
The engine mount made of a rubber material exhibits excellent performance in absorbing and damping vibration with micro amplitude at a high frequency among vibration that occurs when the engine starts, but is very vulnerable to vibration with a large displacement at a low frequency. Thus, the engine mount made of a rubber material does not sufficiently cope with both of the vibration with micro amplitude at the high frequency and the vibration with the large displacement at the low frequency.
Accordingly, a fluid encapsulated engine mount has been used, which absorbs and damps all vibration over widespread ranges including vibration with a micro amplitude at a high frequency and vibration with a large displacement at a low frequency which are input to the engine mount by operating an engine.
In general, in order to improve fuel efficiency of the vehicle, an active mount, a semi-active mount, and the like for preventing noise, vibration, and harshness (NVH) performance from deteriorating, are used. Typically, a semi-active mount controls dynamic characteristics of the mount in an on-off manner.
The semi-active mount is classified into a volume stiffness mount, and a bypass mount, and these mounts have different implementation methods and dynamic characteristics.
The bypass mount has low characteristics (a dynamic ratio of about 0.6) at a low-frequency range (20 to 40 Hz) and is mainly used for a diesel engine since the bypass mount has lower dynamic characteristics in a low frequency range than the volume stiffness mount. Thus, idle performance is maximized.
On the other hand, the volume stiffness mount has lower dynamic characteristics at a high frequency than the bypass mount, and the volume stiffness mount has higher dynamic characteristics at a low frequency than the bypass mount.
The bypass mount, which is typically and commercially available, uses vacuum pressure (at an intake manifold), and thus deteriorating the layout and combustion back pressure.
In comparison with the vacuum pressure mount, the electronic mount uses electromagnetic force generated in a vehicle such that there is no loss of combustion pressure. Accordingly, electric wires (wiring) may be more easily laid out than hoses for transferring vacuum pressure, and as a result, the electronic mount has been used widely.
The present disclosure proposes an electronic semi-active mount.
The above information disclosed in this Background section is only for enhancement of understanding the background of the invention, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.